Aiming at the motion planning problem of dual robots hub grinding system, a motion posture constraint model of coordinated relative motion of dual robots was established, and the calibration problems of base system and tool coordinate system of dual robots were solved by laser tracker and seven-point method respectively. The hub edge surface was selected to build a simulation platform to verify the motion model. Finally, an experimental platform for coordinated grinding of dual robots was built based on dSPACE controller, and the coordinated grinding position tracking experiment was carried out. The results show that the position tracking accuracy of grinding robot is less than 4 mm, which proves the accuracy and feasibility of the model.